Issue Summary

A race condition exists in Jira where attachments can be given the same name when uploaded at the same time instead of having unique numbers appended to them.

Steps to Reproduce

1. Install Jira with a project already set up
2. Create an issue in the newly created project.
3. Obtain the ID of the newly created issue by following the steps in [How to get issue id from the Jira User Interface | Jira and Jira Service Management | Atlassian Support|https://support.atlassian.com/jira/kb/how-to-get-issue-id-from-the-jira-user-interface/].
4. Use a script or use a tool like Burp Suite to connect to the <base_url>/rest/api/2/issue/{issue_id}/attachments endpoint for uploading multiple attachments at the same time

A sample script can be found as an attachment. If using this script:

1. Edit the above script to update the BASE_URL, ADMIN_USERNAME, ADMIN_PASSWORD variables with the correct details for your Jira instance.
2. Edit the above script and update the variable ISSUE_IDS with the issue ID
3. In the same directory as the above script, run the following command to generate a set of test attachment files to be uploaded:
    for i in $(seq 1 5); do echo "Test file ${i}" > test${i}.txt; done

Expected Results

Individual attachments were added to the issue with numbers appended to them to indicate unique files.

Actual Results

The attachments have the same name which can be hard to differentiate.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available.